Republican presidential candidate John McCain has released a new ad featuring shots of Britney Spears and Paris Hilton (Watch above). Both stars appear briefly as a narrator describes Democratic opponent Barack Obama as "the biggest celebrity in the world." The narrator then asks, "Is he ready to lead?" The Obama campaign responded in a statement: "On a day when major news organizations across the country are taking Senator McCain to task for a steady stream of false, negative attacks, his campaign has launched yet another. Or, as some might say, 'Oops! He did it again.'" McCain campaign manager Rick Davis...